Rust proofing process



United States Patent 3,300,346 RUST PROOFING PROCESS Samuel Craig, Epping, New South Wales, Australia, as-

signor to S. Craig Investments Pty. Limited, Greenacre, New South Wales, Australia, a corporation of Australia No Drawing. Filed Mar. 13, 1963, Ser. No. 264,762 Claims priority, application Australia, Apr. 4, 1962, 16,191/ 62 4 Claims. (Cl. 148-616) The present invention relates to a process for protecting articles formed from ferrous metals and alloys thereof from corrosion.

The treatment of cast iron, alloy steel and hardened steels to prevent their corrosion, and more particularly to avoid rusting has been attempted in many different ways, and in general involves a surface coating which may be chemically united with the ferrous metals or otherwise made adherent.

Corrosion and rust-proofing coatings in many cases suffer the disadvantage that they may crack with movement of flexible items such as steel springs, and in respect of nuts and bolts and screws the coating of the screw threaded portions can be stripped when driving the screw and tightening the bolts and nuts, thus destroying the effectiveness of the intended rust proofing. The coatings of the prior art in some instances do not withstand abrasion and consequently their effective protection is limited where rough use, for example in connection with wire baskets, is encountered.

The primary object of the present invention is to overcome the foregoing and other disadvantages of the prior art by providing a method of rust-proofing ferrous metals or ferrous alloys, which achieves a surface impregnation of the metal and provides a durable protective surface which is not removed by flexure of treated items nor by any normal extent of abrasion.

Further objects and advantages of the invention will be made apparent in the following description.

The invention comprises a method of rust-proofing articles made from ferrous metals or ferrous alloys comprising soaking the articles in hot brine solution, washing with water, treating them with a cyanide in aqueous solution, washing with water, pickling them, treating them with a phosphate solution and again washing them with water.

A method of rust-proofing ferrous metals or ferrous alloys in accordance with the invention preferably comprises the steps of soaking the previously cleaned articles in a hot brine solution for a period of 5 to 15 minutes, removing same from the brine and freeing them of adherent brine by dipping or washing in hot water, treating the washed articles in a hot sodium cyanide solution for a period of between 5 and 15 minutes and thereafter thoroughly cleansing the treated articles with water followed by further treatment with hot water, pickling the articles in a hot pickling bath for a sufficient period and thoroughly washing the pickled article with cold and then with hot water, subjecting the pickled articles to the action of a phosphate bath for a period of 5 to 15 minutes at a temperature of the order of 210 F., cleaning the phosphated articles with a light water spray followed by dipping in hot water, then drying the treated articles and steeping them in rust inhibiting oil commercially available under the trademark Rustban.

. The invention further includes an optional further step of applying a further known protective coating such as zinechromate to the articles previously treated in accordance with the above method.

The references herein to ferrous metals or alloys are to be read as referring to such ferrous materials as are normally subject to rusting and as excluding stainless steels and similar rust-resistant ferrous materials and rust proof- ICC ing as meaning a commercially acceptable resistance to rusting rather than to absolute resistance to oxidation for all time.

The invention will now be more fully described with reference to a preferred method in accordance therewith directed to the rust-proofing of carpenters nails.

New rust-free nails were steeped in a brine solution for ten minutes at a temperature of F., the brine being made up by dissolving 1 lb. of sodium chloride per gallon of water. The nails, held in a suitable cage, were removed from the brine and drained free thereof and any residual brine removed by dipping in hot water; the dipped nails were then soaked for ten minutes in a sodium cyanide solution at a temperature of 100 F. for a period of ten minutes (the sodium cyanide solution being made up of /2 lb. sodium cyanide per gallon of water).

The treated nails were removed and cleaned by spraying with water followed by dipping in hot water. The dipped nails were then pickled in a hot solution (100 F.) of commercial hydrochloric acid (made up by adding 10 to 20% of muriatic acid by volume to the volume of water employed). The pickled nails were removed, washed with a water spray and dipped in hot water. The treated nails were then placed in a suitable phosphate bath containing 28% by weight of manganese phosphate for 10 to 15 minutes at a temperature of 210 F. The phosphate bath may be any commercially available phosphating solution.

The phosphate treated nails were then cleaned by light spraying with water and then dipped in hot water and dried. The dried nails were then steeped in the rustinhibiting oil known under the trademark Rust ban 392. The steeped articles were drained free of loosely adherent oil and allowed to dry.

The treated nails are of a darkened gun-metal appearance and by virtue of the fact that the applied coatings having been absorbed into the metal surface, are dry and not greasy to the touch. Nevertheless the treated nails have a reduced coefii-cient of friction and are more readily driven into hardwood than clean untreated nails.

The same applied to self-tapping screws driven into metal.

The treatment of nuts, bolts, screws, and indeed any ferrous metal or ferrous metal alloy articles may be carried out in a similar manner to that described above.

It is further to be noted that the application of brine to ferrous articles is of particular benefit in the treatment of forged articles.

Where the articles to be treated are grease or oil covered or otherwise dirty, they are first treated with a suitable degrea'sing organic solvent such as chlorinated ethylene followed by steeping in a boiling alkaline solution such as caustic soda solution containing 2 lbs. caustic soda per gallon of water and thoroughly cleaned with water before being subjected to the brine treatment and following steps in accordance with the invention.

Nuts and bolts treated in accordance with the method of the invention have been tested by being exposed to highly corrosive conditions for extensive periods, together with untreated nuts and bolts of the same kind for purposes of comparison. The treated nuts and bolts were in good order and could be freely undone, whereas the untreated articles were so highly corroded as to be unserviceable.

It is to be understood that variations and modifications in the specific method above described may readily suggest themselves to skilled workers and such may be made without departing from the scope of the invention as defined in the appended claims.

I claim:

1. A method of rust-proofing articles selected from the group consisting of articles made from ferrous metals and articles made from ferrous alloys comprising soaking the said articles in a solution of sodium chloride of strength 0.4 to 15.0% by weight at a temperature of 80150 F., washing with water, treating them unifor-mly with a cyanide selected from the group of cyanides consisting of sodium cyanide and potassium cyanide in aqueous solution of strength 0.4 to 10.0% by weight at a temperature of 40150 F., washing with water, pickling them uniformly, treating them uniformly with a phosphate solution of strength 2.5 to 20% by weight at a temperature 188220 F. and again washing them with water.

2. The method claimed in claim 1 including also the subsequent step of treating the articles with a rust inhibiting oil of the water displacing type.

3. A method of rust-proofing articles selected from the group consisting of articles made from ferrous metals and articles made from ferrous alloys comprising the successive steps of cleaning the aforesaid articles, soaking them uniformly in a solution of sodium chloride of strength 0.4 to 15.0% by weight at a temperature of 80-150 F. for a period of 5 to minutes, removing same from the brine and freeing them uniformly of adherent brine by treatment with hot water, treating the washed articles with a hot sodium cyanide selected from the group of cyanides consisting of sodium cyanide and potassium cyanide solution of strength 0.4 to 10.0% by weight at a temperature of 40-150 F. for a period of between 5 and 15 minutes and thereafter thoroughly cleansing the treated articles with water followed by further treatment with hot water, pickling the articles in a hot pickling bath, thoroughly washing the pickled articles with cold and then hot water, subjecting the pickled articles to the action of a phosphate bath for a period of 5 to 15 minutes at a temperature of the order of 210 F., cleaning the phosphated articles with a light water spray followed by dipping in hot water, then drying the treated articles and steeping them in a rust inhibiting oil of the water displacing type.

4. A method of rust-proofing articles selected from the group consisting of articles made from ferrous metals and articles made from ferrous alloys comprising the successive steps of cleaning the aforesaid articles, soaking them uniformly in a solution of sodium chloride of strength 0.4-15.0% by weight at a temperature of F. for a period of 5 to 15 minutes, removing same from the brine and freeing them uniformly of adherent brine my treatment with hot water, treating the washed articles with a hot sodium cyanide selected from the group of cyanides consisting of sodium cyanide and potassium cyanide solution of strength 0.4 to 10.0% by weight at a temperature of 40150 F. for a period of between 5 and 15 minutes and thereafter thoroughly cleansing the treated articles with water followed by further treatment with hot water, pickling the articles in a hot pickling bath, thoroughly washing the pickled articles with cold and then hot water, subjecting the pickled articles to the action of a phosphate bath for a period of 5 to 15 minutes at a temperature of the order of 210 F., cleaning the phosphated articles with a light water spray followed by dipping in hot water, then drying the treated articles and subsequently applying a protective coating of zinc chromate thereto.

References Cited by the Examiner UNITED STATES PATENTS 2,370,959 3/1945 Holden. 2,374,356 4/1945 Kueffel et al. 117-10 X 2,389,838 11/ 1945 Bromberg.

OTHER REFERENCES Burns et al.: Protective Coatings for Metals, 2nd ed., 1955, Reinhold Pub. Corp., p. 551.

RALPH S. KENDALL, Primary Examiner. 

1. A METHOD OF RUST-PROOFING ARTICLES SELECTED FROM THE GROUP CONSISTING OF ARTICLES MADE FROM FERROUS METALS AND ARTICLES MADE FROM FERROUS ALLOYS COMPRISING SOAKING THE SAID ARTICLES IN A SOLUTION OF SODIUM CHLORIDE OF STRENGTH 0.4 TO 15.0% BY WEIGHT AT A TEMPERATURE OF 80*-150*F., WASHING WITH WATER, TREATING THEM UNIFORMLY WITH A CYANIDE SELECTION FROM THE GROUP OF CYANIDES CONSISTING OF SODIUM CYANIDE AND POTASSIUM CYANIDE IN AQUEOUS SOLUTION OF STRENGTH 0.4 TO 10.0% BY WEIGHT AT A TEMPERATURE OF 40*-150*F., WASHING WITH WATER, PICKLING THEM UNIFORMLY, TREATING THEM UNIFORMLY WITH A PHOSPHATE SOLUTION OF STRENGHTH 2.5 TO 20% BY WEIGHT AT A TEMPERATURE 188*-220*F. AND AGAIN WASHING THEM WITH WATER. 